AWS EKS eksctl: dirty Bash script - literally, it's a very much WIP - that I put together to quickly bring up / tear down an AWS EKS test/dev cluster when working on my Harness certification

eks.bash

#!/usr/bin/env bash

# This script creates a small dev/test EKS cluster using Spot instances. It is very much a WIP, don't run it blindly!
# You can run ./eks.bash to get a list of the available actions; use ./eks.bash template.create to create a ClusterConfig config-file ready to spin up a new cluster
#
# Shout-outs to:
# 	@totallyGreg [ https://github.com/totallyGreg ]
# 	@Erikdeirdre [ https://github.com/erikdeirdre ]
# For sharing their code which I took as a baseline to work with and from which I learned a few tricks

## Global variables initialization
# AWS-related variables
clusterName=${clusterName:-harness-training}
vcpus=${vcpus:-2}
memory=${memory:-8}
cpu_architecture=${cpu_architecture:-x86_64}
gpus=${gpus:-0}
burst_support=${burst_support:-false}
region=${region:-us-east-2}
eks_config_file=${eks_config_file:-config-file.yaml}
k8s_version=${k8s_version:-1.19}
k8s_context=${k8s_context:-@"$clusterName.$region".eksctl.io}

# Script variables
REALPATH=$(realpath "$0")
DIRNAME=$(dirname "$REALPATH")
DATEANDTIME=$(date +"%Y-%m-%d_%H.%M.%S")
CLUSTER_LOG_NAME="$DIRNAME/$clusterName-$DATEANDTIME"
CLUSTER_LOG_NAME_CREATE="$CLUSTER_LOG_NAME-create.log"
CLUSTER_LOG_NAME_TEARDOWN="$CLUSTER_LOG_NAME-teardown.log"
_confirmAsk=', shall we proceed (YES/n):'

## Functions
# Internal functions
function _help() {
    # Check profile and actions, show a help message if something's wrong
    # This function needs to receive an argument to validate the conditional check for supplied actions
    # when called from a callable function
    # TODO: originally this function used to check just a couple of cases, as it grew over time it now needs a better logic for parsing

    case ${FUNCNAME[1]} in
    template.create)
        [ -z "$AWS_ACCOUNT" ] &&
            echo -e "\nError: missing account identifier" \
                "\nPlease set the environment variable AWS_ACCOUNT with your account identifier" &&
            exit 1

        [ -z "$EKS_SSH_KEY" ] &&
            echo -e "\nError: missing ssh key\nPlease set the environment variable EKS_KEY_SSH with a valid path/to/ssh_public_key" &&
            exit 1
        ;;
    *)
        [ ! -s "$eks_config_file" ] &&
            echo -e "\nError: missing eksctl configutarion file" \
                "\nConfig file $eks_config_file not found, run $0 template.create to create a new one" &&
            exit 1

        [ -z "$AWS_PROFILE" ] &&
            echo -e "\nError: missing profile id" \
                "\nAWS_PROFILE environment variable not set" &&
            exit 1

        [ $# -eq 0 ] && echo -e "\nError: no action supplied\n" \
            "Possible actions are:\n-------- ------- ---" &&
            grep -E '^[[:space:]]*([[:alnum:]_]+[[:space:]]*\(\)|function[[:space:]]+([^_].*?)+[[:alnum:]_]+)' "$REALPATH" | awk -F' ' '{print $2}' &&
            exit 1
        # Scan this script for lines beginning with the word function, ignoring "internal" functions which begin with an underscore
        ;;
    esac
}

function _confirm() {
    # Call with a prompt string or use the default string
    read -r -p "${1:-Are you sure? [YES/n]} " response
    case "$response" in
    [Y][E][S] | [Y])
        true
        ;;
    *)
        false
        ;;
    esac
}

function _cluster.up() {
    echo "Using config file $eks_config_file"
    time eksctl create cluster -f "$eks_config_file" --auto-kubeconfig 2>&1 | tee "$CLUSTER_LOG_NAME_CREATE" &&
        echo "Logs written to file $CLUSTER_LOG_NAME_CREATE" &&
        return

    echo "There was an error while creating the cluster, check logfile $CLUSTER_LOG_NAME_CREATE for details" &&
        exit 1
}

function _cluster.delete() {
    _confirm "About to remove cluster $clusterName and its associated resources$_confirmAsk" &&
        time eksctl delete cluster "$clusterName" 2>&1 | tee "$CLUSTER_LOG_NAME_TEARDOWN" &&
        echo "Logs written to file $CLUSTER_LOG_NAME_TEARDOWN" &&
        return

    echo -e "\nTeardown cancelled by the user, no actions performed on the cluster" &&
        exit 0
}

function _write-kubeconfig() {
    eksctl utils write-kubeconfig -c "$clusterName" -r "$region" &&
        echo 'K8s config updated (~/.kube/config)' &&
        return ||
        echo 'There was an error updating the K8s configuration file (~/.kube/config)' &&
        exit 1
}

# Callable functions
function cluster.teardown() {
    _help h
    profile.set
    time _cluster.delete &&
        echo "The cluster $clusterName and its associated resources have been destroyed" &&
        exit 0
}

function cluster.create() {
    _help h

    local iam_user

    echo 'Acquiring AWS IAM UserName to setup EKS context...'
    iam_user="$(aws --output=yaml iam get-user --query 'User.UserName' | sed -e 's/^"//' -e 's/"$//')"
    [ -z "$iam_user" ] && echo 'There was an error retrieving current IAM user, please check your credentials an environment variables and try again' &&
        exit 1 ||
        echo "UserName is: $iam_user"

    echo -e "\nSpinning up $clusterName EKS cluster..."
    profile.set &&
        time instances.get &&
        time _cluster.up &&
        time _write-kubeconfig &&
        kubectl config use-context "$iam_user$k8s_context" &&
        kubectl config set-context --current --namespace=default &&
        echo "K8s context set to $iam_user$k8s_context, namespace: default" &&
        exit 0
}

function instances.get() {
    instances="$(ec2-instance-selector --vcpus="$vcpus" --memory="$memory" --cpu-architecture="$cpu_architecture" --gpus="$gpus" --burst-support="$burst_support" |
        paste -d, -s -)"
    echo "Using instances type: $instances" &&
        return ||
        echo 'There was an error acquiring the instances types' &&
        exit 1
}

function profile.set() {
    echo "AWS profile set to $AWS_PROFILE"
}

function template.create() {
    _help h

    local attachedPolicyARN
    attachedPolicyARN=${attachedPolicyARN:-arn:aws:iam::"$AWS_ACCOUNT":policy/SecretsManager-bare}

    local publicKeyPath
    publicKeyPath=${publicKeyPath:-"$EKS_SSH_KEY"}

    [ -f "$eks_config_file" ] &&
        echo "Error: $eks_config_file already exists and will be overwritten" &&
        exit 1

    # TODO: this heredoc isn't fully templetized yet
    cat <<EOF >"$eks_config_file"
apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig

metadata:
    name: $clusterName
    region: $region
    version: "$k8s_version"

managedNodeGroups:
  - name: ng-spot
    instanceTypes: ["m5.large","m5a.large","m5ad.large","m5d.large","m5dn.large","m5n.large","m5zn.large"]
    desiredCapacity: 2
    minSize: 2
    maxSize: 2
    privateNetworking: true
    volumeSize: 10
    ssh:
      allow: true
      publicKeyPath: $publicKeyPath
      enableSsm: true
    iam:
      attachPolicyARNs:
      - arn:aws:iam::aws:policy/AmazonEKSWorkerNodePolicy
      - arn:aws:iam::aws:policy/AmazonEKS_CNI_Policy
      - arn:aws:iam::aws:policy/AmazonEC2ContainerRegistryReadOnly
      - $attachedPolicyARN
    volumeType: gp2
    spot: true
EOF

    # Check the config file was successfully created and has a size greater than zero
    [ -s "$eks_config_file" ] &&
        echo -e "\nConfiguration file $eks_config_file successfully created" \
            "\nIf it looks good to you, run $0 cluster.create to begin creating the cluster" &&
        exit 0 ||
        echo "There was an error creating the configuration file $eks_config_file" &&
        exit 1
}

## Run action
[ $# -eq 0 ] && _help || "$@"